Add support for allowEmptyValue (#515)

Co-authored-by: Pierre Fenoll <[email protected]>

Author: Yarn-e

openapi3filter/fixtures/petstore.json

@@ -211,6 +211,111 @@
         ]
       }
     },
+    "/pets/": {
+      "get": {
+        "tags": [
+          "pet"
+        ],
+        "summary": "Find pets by the specified filters",
+        "description": "Returns a list of pets that comply with the specified filters",
+        "operationId": "findPets",
+        "parameters": [
+          {
+            "name": "status",
+            "in": "query",
+            "description": "Status values that need to be considered for filter",
+            "required": false,
+            "explode": true,
+            "allowEmptyValue": true,
+            "schema": {
+              "type": "array",
+              "items": {
+                "type": "string",
+                "enum": [
+                  "available",
+                  "pending",
+                  "sold"
+                ],
+                "default": "available"
+              }
+            }
+          },
+          {
+            "name": "tags",
+            "in": "query",
+            "description": "Tags to filter by",
+            "required": false,
+            "explode": true,
+            "schema": {
+              "type": "array",
+              "items": {
+                "type": "string"
+              }
+            }
+          },
+          {
+            "name": "kind",
+            "in": "query",
+            "description": "Kinds to filter by",
+            "required": false,
+            "explode": false,
+            "style": "pipeDelimited",
+            "schema": {
+              "type": "array",
+              "items": {
+                "type": "string",
+                "enum": [
+                  "dog",
+                  "cat",
+                  "turtle",
+                  "bird,with,commas"
+                ]
+              }
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "successful operation",
+            "content": {
+              "application/xml": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "allOf": [
+                      {"$ref": "#/components/schemas/Pet"},
+                      {"$ref": "#/components/schemas/PetRequiredProperties"}
+                    ]
+                  }
+                }
+              },
+              "application/json": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "allOf": [
+                      {"$ref": "#/components/schemas/Pet"},
+                      {"$ref": "#/components/schemas/PetRequiredProperties"}
+                    ]
+                  }
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "Invalid status value"
+          }
+        },
+        "security": [
+          {
+            "petstore_auth": [
+              "write:pets",
+              "read:pets"
+            ]
+          }
+        ]
+      }
+    },
     "/pet/findByTags": {
       "get": {
         "tags": [

openapi3filter/internal.go

@@ -1,6 +1,7 @@
 package openapi3filter
 
 import (
+	"reflect"
 	"strings"
 )
 
@@ -11,3 +12,14 @@ func parseMediaType(contentType string) string {
 	}
 	return contentType[:i]
 }
+
+func isNilValue(value interface{}) bool {
+	if value == nil {
+		return true
+	}
+	switch reflect.TypeOf(value).Kind() {
+	case reflect.Ptr, reflect.Map, reflect.Array, reflect.Chan, reflect.Slice:
+		return reflect.ValueOf(value).IsNil()
+	}
+	return false
+}